Ceramic refractory flame retention nozzle



Nov. 14, 1967 J. T. ROBSON 3,352,347v

CERAMIC REFRACTORY FLAME RETENTION NOZZLE Filed Oct. 50, 1963 F163 INVENTOR JAMES T. ROBSON ATTORNEY United States Patent Ohio Filed Oct. 30, 1963, Ser. No. 320,609 Claims. (Cl. 158116) This invention deals generally with gas burners, and deals more particularly with a flame retention device for gas burners for ceramic kilns and the like.

As is well known, gas burners provide an ideal means for supplying heat to various types of heat treating furnaces, particularly kilns designed for the firing of ceramic and enamel ware. One of the drawbacks to burners utilized heretofore for the combustion of a gas-air mixture for firing ceramic ware, has been the fact that the nozzle (that part of the burner wherein combustion is initiated) being of metal, has shown a tendency to break down under the tremendously severe conditions of heat shock and temperature, thereby shortening its life, and at the same time distributing contaminants into the atmosphere surrounding the ceramic ware to be fired in the form of oxidized metal particles which slough off from the burner and are carried into the kiln by the blast of the burning fuel-air mixture.

It is therefore an object of this invention to provide a flame retention nozzle for a fuel-air burner to efliciently and continuously provide a sustained gas flame.

It is a further object of this invention to provide a flame retention nozzle for a hydrocarbon fuel-air burner having a prolonged life and freedom from a tendency to break down and contribute oxidized metallic particles into the atmosphere of a ceramic kiln.

Briefly and simply stated, my invention consists of a flame retention nozzle comprising a tubular housing having a fuel-air inlet end, and a flame discharge end, said nozzle having disposed within its interior, between its two ends, and generally at right angles to the long axis of the nozzle, a perforate diaphragm, said diaphragm having a centrally located aperture having a diameter at least a third of the inside diameter of said tubular housing, said diaphragm having a multiplicity of perforations therethrough, smaller than said centrally located aperture and generally symmetrically distributed around said aperture, said nozzle composed of a ceramic refractory, preferably a ceramic refractory containing a minimum of 95% A1203 In the attached drawings, FIG. 1 is a perspective view of my novel flame retention nozzle,

FIG. 2 is a cross-section through the Section 22 of FIG. 1, and

FIG. 3 is a variation of the basic flame retention nozzle, shown in cross-sectional view taken through the section 3-3 of FIG. 1.

In operation, the flame retention nozzle designated generally by the reference numeral 1 is threaded to a conventional pipe of suitable diameter, not shown, which delivers the proper hydrocarbon fuel-air mixture to said nozzle from a source not shown, using conventional pumping and conveying means.

Referring to FIGS. 2 and 3, the arrow depicts the direction of entry of the fuel-air mixture through the fuel inlet end of flame retention nozzle 1 under pressure, whereupon said mixture under pressure immediately encounters restrictive diaphragm 3, having aperture 4 centrally located therein which acts as a nozzle to aid in accelerating the discharge of the fuel-air mixture from the flame discharge end 5 of said nozzle to induce the flame 6 to penetrate the combustion zone of the kiln, furnace, etc. being heated. Pilot perforations 7 aid in 'ice maintaining a constant flame in that the fuel-air mixture being forced through pilot perforation 7 results in a short confined pilot flame 8 which cannot be readily extinguished since pilot combustion takes place within the confines of the flame retention nozzle as shown. Thus, if for some reason the primary flame 6 is extinguished, sustained pilot flames 8 will immediately re-ignite the fuelair mixture to maintain flame 6 under practically all conditions, thereby eliminating a safety hazard and assuring constant, uniform heat in the kiln or furnace being fired. As shown, pilot perforations 7 are preferably set at an angle as shown to induce pilot flames 8 to be deflected from the interior surface of the nozzle toward its central axis to maintain the pilot flames in continual contact with the main fuel stream.

FIG. 3 depicts another version of the flame retention nozzle shown in FIG. 2, the dished diaphragm 2 improving the flow characteristics of the fuel-air mixture through aperture 4 and at the same time setting pilot perforations 7 back rearwardly somewhat of aperture 4 as an added aid to protection of pilot flames 8.

I have found that, by manufacturing my novel nozzle, using conventional methods of manufacture, from a ceramic refractory, which term has a well defined meaning in the art, that I am able to completely eliminate coutamination of ceramic ware from metallic contaminants emanating from the burner nozzle and I have further greatly increased the life of the flame retention nozzle made from a ceramic refractory. Preferably, my refractory material is one of those well known in the art, consisting of a minimum of A1 0 Due to the difference in expansion characteristics between my refractory flame retention nozzle and the pipe or duct used to deliver the fuel-air mixture to the flame retention nozzle, I have found it necessary to thread the fuel inlet end of my flame retention nozzle on the exterior surface thereof, to make it adaptable to be received by the fuel-air delivery duct in a female thread cut in said duct. In this way, the greater expansion of the metallic duct, or pipe, under high temperatures, does not have the effect of crushing or breaking the ceramic flame retention nozzle.

I consider the use of a ceramic material for this particular application as novel since, as is well known, ceramic materials, even highly refractory ceramic materials, have always been considered extremely susceptible to the severe heat shock conditions resulting when a piece, such as my flame retention nozzle for example, reposing at room temperature, is suddenly made part of an environment involving an extremely high temperature gas flame, with equally shocking conditions occurring when the flame is suddenly extinguished after use, and there is a sudden cooling of the nozzle.

Surprisingly, however, I have found that the tubular design of the flame retention nozzle, whereby the walls of the nozzle are of substantially uniform thickness, plus the fact that the high percentage of alumina in my refractory, at least 95%, provides a sufficiently low coeflicient of expansion, permits this particular application for a ceramic refractory. This of course is primarily theory and I do not wish to be bound thereby; suflice it to say that I, and those skilled in the art, would consider it surprising that a ceramic refractory would effectively function in the manner and form above described.

Accordingly, having described my invention, I claim:

1. In a flame retention nozzle comprising a unitary, non-perforate tubular housing having a fuel inlet end and a flame discharge end, said nozzle having disposed within its interior, between said two ends, and generally at right angles to the long axis of said housing, a perforate diaphragm integral with said tubular housing, said diaphragm having a centrally located aperture having a di- 2. In a flame retention nozzle comprising a unitary,

non-perforate tubular housing having a fuel inlet end and a flame discharge end, said nozzle having disposed within its interior, between said two ends, and generally at right angles to the long axis of said housing and integral therewith, a perforate dished diaphragm having its convex surface toward said flame discharge end, said diaphragm having a centrally located aperture having a diameter at least one third the inside diameter of said tubular housing, said diaphragm having a multiplicity of perforations therethrough smaller than said centrally located aperture, said multiplicity of perforations distributed generally symmetrically around said aperture, said nozzle composed of a ceramic refractory.

3. In a flame retention nozzle comprising a unitary, non-perforate tubular housing having a fuel inlet end and a flame discharge end, said nozzle having disposed within its interior, between said two ends, and generally at right angles to the long axis of said housing and integral therewith, a perforate dished diaphragm having its convex surface toward said flame discharge end, said diaphragm having a centrally located aperture having a -diameter at least one third the inside diameter of said tubular housing, said diaphragm having a multiplcity of perforations therethrough smaller than said centrally located aperture, said multiplicity of perforations distributed generally symmetrically around said aperture, said nozzle composed of a ceramic refractory consisting of at least 95% A1 4. In a flame retention nozzle comprising a unitary, non-perforate tubular housing having a fuel inlet end and a flame discharge end, said nozzle having disposed within its interior, between said two ends, and generally atiright angles to the long axis of said housing and integral therewith, a perforate diaphragm, said diaphragm having a centrally located aperture having a diameter at least one third the inside diameter of said tubular housing, said diaphragm having a multiplicity of perforations therethrough smaller than said centrally located aperture, said multiplicity of perforations distributed generally symmetrically around said aperture, said nozzle composed of a ceramic refractory consisting of at least Al O 5. In a flame retention nozzle comprising a unitary, non-perforate tubular housing having a fuel inlet end and a flame discharge end, said nozzle having disposed within its interior, between said two ends, and generally at right angles to the long axis of said housing and integral therewith, a perforate diaphram, said diaphragm having a cen trally located aperture having a diameter at least one third the inside diameter of ,said tubular housing, said diaphragm having a multiplicity of perforations therethrough smaller than said centrally located aperture, said multiplicity of perforations distributed generally symmetrically around said aperture, said nozzle composed of at least 95% A1 0 the fuel inlet end of said nozzle having a male thread cut thereon to adapt same to be received by a corresponding female thread on the inside diameter of a fuel supply duct.

References Cited UNITED STATES PATENTS 1,763,289 6/1930 Anderson et al. 2,386,882 10/1945 Reagan et al. 158-7 2,525,432 10/1950 Stadler 158ll6 2,669,300 2/1954 Blaha 158-116 2,888,980 6/1959 Williams et al. 158116 FREDERICK L. MATTESON, JR., Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,352,347 November 14, 1967 James T. Robson It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, lines 54 and 55, strike out "taken through the section 3-3 of FIG. 1''; column 2, line 38, after "the" insert conventional same line 38, after "duct" insert (not shown) line 60, beginning with suffice it to say" strike out all to and including "above described" in line 63, same column 2..

Signed and sealed this 10th day of December 1968.

(SEAL) Attest:

Edward M. Fletcher, Jr. EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. IN A FLAME RETENTION NOZZLE COMPRISING A UNITARY, NON-PERFORATE TUBULAR HOUSING A FUEL INLET END AND A FLAME DISCHARGE END, SAID NOZZLE HAVING DISPOSED WITHIN ITS INTERIOR, BETWEEN SAID TWO ENDS, AND GENERALLY AT RIGHT ANGLES TO THE LONG AXIS OF SAID HOUSING, A PERFORATE DIAPHRAGM INTEGRAL WITH SAID TUBULAR HOUSING, SAID DIAPHRAGM HAVING A CENTRALLY LOCATED APERTURE HAVING A DIAMETER AT LEAST ONE THIRD THE INSIDE DIAMETER OF SAID TUBULAR HOUSING, SAID DIAPHRAGM HAVING A MULTIPLICITY OF PERFORATIONS THERETHROUGH SMALLER THAN SAID CENTRALLY LOCATED APERTURE, SAID MUTLIPLICITY OF PERFORATIONS DISTRIBUTED GENERALLY SYMMETRICALLY AROUND SAID APERTURE, SAID NOZZLE COMPOSED OF A CERAMIC REFRACTORY. 